Process for oxidizing a 1 1-bis(alkylphenyl) alkane

ABSTRACT

A PROCESS OF OXIDIZING A 1,1-BIS(ALKYLPHENYL)ALKANE TO CONVERT ALKYL SUBSTITUENTS TO CARBOXYLIC ACID SUBSTIUENTS WHICH INVOLVES CONTACTING THE 1,1-BIS(ALKYLPHENYL)ALKANE WITH OXYGEN IN A LOWER CARBOXYLIC ACID CONTAINING COBALT AND A METHYLENIC KETONE.

PROCESS FOR OXIDIZING A 1,1-BIS(ALKYL- PHENYL)'ALKANE 1 .1" Anatoli Onopchenko, Mon'roeville, Johann G, D, Schulz,

Pittsburgh, and RichardSeekircher, Cheswick, Pa., as-.

signors to Gulf Research dz l)ev elopn1ent Company,

Pittsburgh, Pa. V No Drawing. Filed May 8, 1970, Ser. No. 135,822 7. Int. Cl. C07c 63/02, 65/20 US. Cl. 260-524 R I 16 Claims This invention relates to a process for oxidizing a 1,1-

bis alkylphenyl alkane. In US. Pat."No'.'3,424,789' of Schulz et al., a l,l-bis- (alkylphenyl)alkane-was subjected to oxidation by contacting the sameat elevated temperatures with molecular oxygen in the presenceof a transition metal salt of a carboxylic acid andf methyl ethyl ketone. Unfortunately, not all of the alkyl substituentson the phenyl rings were converted to carboxylic acid "substituents and it was found necessary to complete the conversion of the alkyl substituents by subjecting'the initially oxidized product to further oxidation with nitric acid. In addition, in each case the 1,1-bis(alkylphenyl)alkane was converted to the corresponding benzophenone.

It has now been found that when the process defined above is carried out in the presence of a lower carboxylic acid, each of the alkyl substituents' on the phenyl ring cangbe converted to a carboxylic acid substituent, and that by varying the amounts of methylenic ketone employed, oxidation can be controlled so that (l) substantially none of the alkane bridge is oxidized, 2) substantially all of the'alkane bridge is converted toa carbonyl bridge or (3) only a portion of the alkane bridge is converted to a carbonyl bridge. Y

The l,l-bis(alkylphenyl)alkane that is subjected to treatment herein is one wherein each phenyl group carries from one to five alkyl groups, preferably from one to two alkyl groups, each alkyl group having from one to 16 carbon atoms, preferably from one to eight carbon atoms,

and said alkane bridge'has from two to 16 carbon atoms, preferably from two to eight carbon atoms. Of these, 1,1- bis(alkylphenyl)alkanes are preferred. Specific examples of 1,l-bis(alkylphenyl)alkanes that can be employed include 1, l-bisp-tolyl) ethane,

' 1,1-bis-(p-tolyl)propane,

1,1-bis-(p-tolyl)-hexane,

1 l-bis- (p-tolyl) octane,

1,l-bis-(p-tolyl)decane, I, v l,l-bis-(p-tolyl)dodecane, 1,l-bis-(p-tolyl)tetradecane, 1, l-bisp-tolyl) hexadecane, 1,1-bis-(4-ethylphenyl)ethane,

1 ,1-bis-(4-octylphenyl) pentane, 1,l-bis-(4-decylphenyl)octane,

1, l-bis- (4-hexadecylphenyl) hexadecane,

1, l-bis 3,4-dimethylphenyl ethane, 1,1-bis-(3,4-dimethylphenyl)propane, 1,l-bis-(3,4-dimethylphenyl)butane,

3,641,136 Patented Feb. 8, 1972 l-bis- 2,2-dibromo,3,4,3',4-tetramethylphenyl ethane, (3 -methyl-4-ethylphenyl) 2'-nitro,3 4-diethylphenyl) ethane, l-bis-( 3,4,3',4'-tetramethyl-S-aminophenyl ethane, 3,4-diethylphenyl) 3,4-diisopropylphenyl)ethane, -(2-methyl-4-isopropylpheny1) 4-methyl-2-nitrophenyl) ethane, 1,1-bis-(3 -ethyl-4-butylphenyl is obutane, 1-( -p p ph y 1-(2-ethylphenyl) octane, 1, l-bis- 2,4-diisopropylphenyl hexadecane, 1,1-bis-(2-ethyl,4-butylphenyl)-isobutane, etc.

The reaction defined herein can be carried out by bringing together the l,l-bis(alkylphenyl)alkane, molecuular oxygen, cobalt, methylenic ketone and a lower carboxylic acid at moderate temperatures and pressures.

The molar amount of molecular oxygen needed is 1.5 mols foreach alkyl substituent converted to carboxylic acid substituent, and to the extent the alkane bridge is converted to carbonyl, 2 mols per mol of alkane bridge converted. To assure the desired oxidation, about 1 to about molar excess of molecular oxygen can be used.

Also present in the reaction mixture is cobalt, which can be added in any form, but is preferably added as a salt soluble in the reaction mixture. Thus, the cobalt compound can be in the form of an inorganic compound or as an organic compound, for example, as a cobaltous or cobaltic chloride, sulfate, nitrate, acetate, propionate, butyrate, isovalerate, benzoate, toluate, naphthenate, salicylate, acetyl acetonate, etc. The amount of cobalt compound employed, as cobalt, based on the total reaction mixture is from about 0.1 to about 15 percent, preferably from about 0.3 to about 5 percent by weight.

Additionally required herein as activator is a methylenic ketone, such as methyl ethyl ketone, methyl propyl ketone, diethyl ketone, acetylacetone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, l-tetralone, 2-tetralone, l-decalone, Z-decalone, etc. Of these, methyl ethyl ketone is preferred. The amount of methylenic ketone can be from about 0.01 to about 50 mols per mol of l,l-bis(alkylphenyl)alkane, preferably from about 0.5 to about 5 mols per mol of 1,1-bis(alkylphenyl)alkane.

Decreasing the amount of methylenic ketone employed herein increases the yield to diphenyl alkane acids and decreases the yield to benzophenone acids, while increasing the amount of methylenic ketone decreases the yield to diphenyl alkane acids and increases the yield to benzo- "phenone acids.

" As pointed out above, it is critical that there also be "present in the reaction mixture a lower carboxylic acid, that is, one having from two to six carbon atoms, preferably from about two to four carbon atoms. Specific Reaction conditions are mild. Thusjthe temperature can .be fromabout 60? .to. about.20.0.. .C., preferably.ir.om.- s-..-

about 90 to about 125 C., and the pressure can be from about atmospheric to about 5000 pounds per square inch gauge, preferably from about 100 to abouth500 pounds per square inch gauge. A residence timeofxa'bouti one minute to about 60 hours, preferably from abouttwoito about 12 hours, can be used. a I The desired compounds can be recovered from the reaction product in any convenient manner. For example, at the end of the reaction period the reaction product is brought to atmospheric conditions, resulting in the precipitation of benzophenone and/ or diphenyl alkane aacids. Upon filtration, the latter two materials are separated from each other by treatment with acetone, since the diphenyl alkane acids are soluble therein. The filtrate containing the lower carboxylic acid, cobalt and unoxidized and/or partially oxidized charge is then returned to the oxidation stage for conversion to additional desired product.

The process can further be illustrated by the following. In each of the runs there was introduced into a one-liter, 316-stainless steel, magnetically-stirred autoclave, glacial acetic acid, cobaltous acetate tetrahydrate, 1,1-bis (p-tolyl) ethane and methyl ethyl ketone. The autoclave was raised to a reaction temperature of 105 C. and pressured with molecular oxygen to a pressure level of 300 pounds per square inch gauge and maintained under these conditions throughout the duration of the runs. In each of the first two runs the reaction was permitted to go for a period of six hours, during which time 100 percent of the charge was converted. In the third run, reaction was terminated prematurely at the end of 5.8 hours, at which time 68 percent of the charge had been converted. The autoclave at the end of the reactions was cooled, depressured, and the product mixture removed therefrom and filtered to recover white solids, which were washed with water, dilute hydrochloric acid, again water and then dried in a vacuum oven. The filtrate was evaporated to dryness and the residue extracted with acetone to remove organic matter from the catalyst. On evaporation of acetone, additional solid product was obtained. The cobalt catalyst was treated with hydrochloric acid, filtered and washed with water to afford several additional grams of product. The total solids recovered were subjected to analysis by chromatography. The results obtained are tabulated below in Table I.

TABLE I Run No I II III Charge data (grams):

Acetic acid 525 525 525 Cobaltcus acetate tetrahydrate 31. 5 31. 5 31. 5 1,1-bis(p-tolyl)ethane 52. 0 43. 8 43. 8 Methyl ethyl ketone 80 40 20 Percent selectivity to Benzophenone dicarboxylic acids alld precursors thereof. 22 17. 8 12 Diphenyl ethane dicarboxylic acids and precursors thereoL 65 69 76 The uniqueness of the present procedure is apparent from the above. With acetic acid present, conversion of alkyl substituents to carboxylic acid substituents is effected without the need of an additional chemical oxidant, and selectivity to benzophenone diacids and diphenylethane diacids is seen to be a direct function of the amountof methylenic ketone present. The diphenylethane polycarboxylic acids obtained herein can be used to react with monocarboxylic acids can be further oxidized inacco'rdancemith.theproceduredefined herein. to obtain diphenylethane polycarboxylic acidsor they can be used in cornbination with the diphenylethane polycarboxylic acids in the reactions defined above to terminate the reaction of the diphenylethane polycarboxylic acids with the polyhydric'alcohols' or with the-diamines Qbviously, many modifications" and variations of the invention, ashereirlabove' set forth, can be'made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims a We claim: I

1. A process for oxidizing a l,l.-bis(alkylphenyl') alkane, wherein the alkane bridge has from two to 16 carbon atoms, to convert alkyl substituents to carboxylic acid substitutents which consists in contacting said 1,1-bis (alky1phenyl)alkane with molecular oxygen in a lower carboxylic acid containing cobalt and'a methylenic ketone.

2. The process of claim 1 wherein said 1, 1-bis-(alkylphenyl alkane is 1,1-bis ptolyl ethane.

3. The process of claim 1 wherein 'said lower carboxylic acid has from two to six carbon atoms.

4. The process of claim 1 wherein said lower carboxylic acid has from two to four carbon atoms.

5. The process of claim 1 wherein said lower carboxylic acid is acetic acid.

6. The process of-claim 1-wherein said-lower carboxylic acid and said 1,1bis(alkylphenyl)alkane'are present in a weight ratio of about "1:1 to about 50:1.

7. The process of claim 1 wherein saidlower carboxylic acid and said l,1-bis(alkylphenyl)alkane are present in a weight ratio of about 5:1 to about 20:1.

8. The process of claim 1 wherein said cobalt is obtained from a cobalt salt soluble in the reaction mixture.

9. The process of claim 1 wherein said cobalt is obtained from cobaltous acetate tetrahydrate;- I

10. The process of claim: 1 wherein the amount of cobalt employed is from about 0.1-to about 15 percent, by weight based on the, total reaction mixture.

11. The process of claim 1 wherein the amount of cobalt employed is from about 0.3 to about five percent by weight based on the total reaction mixture.

12. The process of-claim 1 wherein said methylenic ketone is methyl ethyl ketone.

13. The process of claim 1 wherein the amount of methylenic ketone-isfrom about 0.01 to about 50 mols per mol of said l,l-bis(alkylphenyl)alkane.

14. The process of claim 1 wherein the amount of methylenic ketone is from about 0.5 to about 5 mols. per mol of said 1,1-bis(alkylphenyl)alkane. 1

15. The process of claim 1 wherein the reaction is carried out in a temperature range :of about,60 to about 200 C. a, a.

16. The process of claim 1 wherein the reaction is carried out in a temperature range of about to about C.- 1

References Cited V UNITED STATES PATENTS 3,467,698 9/1969 Schulz et al 260524 2,853,514 9/1958 Brill 260-524 JAMES A. PATTEN, Primary Exam. 2

R. S. WEISSBERG, Assistant Examiner- Us. 01. X.R. j 260517 

